P8086

MyStack segment stack
  DB 64 dup('12345678')
MyStack endS
MyData segment
  ; --- Declare your variables here ---
  prompt1 DB "Which background? (0-31): $"
  prompt2 db "Which palette? (0-1): $"
  back db 01h
  pal db 01h
  cpixl db 0c0h
  cmask db 03fh
  xpos dw 160
  ypos dw 100
  color db 03h
  MyData endS
MyCode segment                                  ; Sets up the segment names for
 Assume CS:MyCode,ES:MyData
include CONIO.INC
include time.inc


GetMask proc
mov ax,xpos
mov bl,04h
div bl
mov cl,3
sub cl,ah
mov ah,color
shl ah,cl
shl ah,cl
mov cpixl,ah
mov ah,03h
shl ah,cl
shl ah,cl
not ah
mov cmask,ah
ret
GetMask endp

CheckKeys proc
mov ah,08h
int 21h
cmp al,48h
je up
cmp al,4bh
je left
cmp al,4dh
je right
cmp al,50h
je down
jmp keysEnd
;We can butcher ax now. Yay.
up:
cmp ypos,00h
jle keysEnd
dec ypos
mov ax,ypos
mov bl,02h
div bl
cmp ah,0
je evenUp
add di,02000h
sub di,80 ; 320/4
jmp keysEnd
evenUp:
sub di,02000h
jmp keysEnd


left:
cmp xpos,0
jle keysEnd
dec xpos
mov ax,xpos
mov bl,04h
div bl
cmp ah,3
jne keysEnd
sub di,1
jmp keysEnd

right:
cmp xpos,319
jge keysEnd
inc xpos
mov ax,xpos
mov bl,04h
div bl
cmp ah,0
jne keysEnd
add di,1
jmp keysEnd

down:
cmp ypos,199
jge keysEnd
inc ypos
mov ax,ypos
mov bl,02h
div bl
cmp ah,0
je evenDown
add di,02000h
jmp keysEnd
evenDown:
sub di,02000h
add di,80 ; 320/4
keysEnd:
ret
CheckKeys endp

clearscreen proc
push di
mov di,0
MOV CX,320*200

FillScreenLoop:
     MOV BYTE PTR [DI],00h
 inc di
 LOOP FillScreenLoop
pop di
ret
clearscreen endp

sketch proc
mov ah,0
  mov al,04h
  int 10h
  mov ah,0Bh
  mov bh,0
  mov bl,back
  int 10h
  mov ah,0Bh
  mov bh,1
  mov bl,pal
  int 10h
  MOV AX,0B800h
  MOV DS,AX
  mov di,0fc8h


 loopy:
 mov bl,BYTE PTR [DI]
 and bl,cmask
 or bl,cpixl
 mov BYTE PTR [DI],bl
 MOV AH,08h
 INT 21h
 cmp al,1bh
 je quit
 cmp al,09h
 jne noTab
 inc color
 cmp color,3
 jle noTab
 mov color,0
 noTab:
 cmp al,20h
 jne noClear
 call clearScreen
 noClear:
 cmp al,00h
 jne ender
 call checkKeys
 call getMask
 ender:

 jmp loopy
 quit:
 MOV AH,0
      MOV AL,03h                    ;Restore the screen mode to 03h (the text screen).
      INT 10h
ret
sketch endp

Main PROC                                      ; Main procedure
  Start:
  MOV AX, MyData
  MOV ES, AX
  mov DS, AX
  enterBG:
  MOV AH,9

  LEA DX,ES:prompt1             ; Let DS:DX = offset of "prompt" within DS.
  INT 21h
  CALL InputDecWord
  cmp al,31
  jg enterBG
  cmp al,0
  jl enterBG
  mov back,al
  enterPal:
  MOV AH,9
  LEA DX,ES:prompt2             ; Let DS:DX = offset of "prompt" within DS.
  INT 21h
  CALL InputDecWord
  cmp al,1
  jg enterPal
  cmp al,0
  jl enterpal
  mov pal,al


  call sketch
  mov ah, 4ch
  xor al, al
  int 21h
Main ENDP

MyCode endS
End Start